System and method for reducing engine knock

ABSTRACT

A method includes operating a spark ignition engine and flowing low pressure exhaust gas recirculation (EGR) from an exhaust to an inlet of the spark ignition engine. The method includes interpreting a parameter affecting an operation of the spark ignition engine, and determining a knock index value in response to the parameter. The method further includes reducing a likelihood of engine knock in response to the knock index value exceeding a knock threshold value.

CROSS-REFERENCE TO RELATED APPLICATIONS:

The present application is a continuation of U.S. patent applicationSer. No. 16/036,056 filed Jul. 16, 2018, which is a divisional of U.S.patent application Ser. No. 14/605,358 filed on Jan. 26, 2015, issued asU.S. Pat. No. 10,024,253 on Jul. 17, 2018, which is a continuation ofInternational Patent App. No. PCT/US2013/053094 filed on Jul. 31, 2013,which claims priority to, and the benefit of the filing date of, U.S.Provisional App. No. 61/677,671 filed Jul. 31, 2012, each of which isincorporated herein by reference for all purposes in its entirety.

BACKGROUND

The present application relates to engine control systems and moreparticularly, but not exclusively, to engine control systems forcontrolling knock within spark-ignition gasoline engines.

Internal combustion engines can generally be grouped into one of twoclasses: spark-ignition and compression-ignition engines. Spark-ignitionengines typically operate by introducing a stoichiometric mixture of airand fuel into a cylinder of an engine. A piston then compresses thismixture, and at a predetermined crankshaft angle, a spark plug willignite the air/fuel mixture producing a flame front that propagatesthrough the combustion chamber. The rapid increase in heat from theburned fuel triggers an increase in pressure which forces the pistondownward in the cylinder. The ability to precisely time the combustionevent through the use of a spark plug is a benefit of the spark-ignitionengine. However, the spark-ignition engine may be somewhat inefficientsince the compression ratio of the engine is kept to a relatively lowlevel to avoid “knock.” Knock occurs when the air/fuel mixture ignitesindependently of the spark plug and may cause engine damage.Consequently, spark-ignition engines typically have compression ratiosin a range of 8 to 11.

The compression-ignition engine, on the other hand, operates atrelatively high compression ratio that is typically within the range of15 to 22. This high compression ratio boosts the mechanical efficiencyof the compression-ignition engine. The compression-ignition engineoperates by introducing unthrottled air into the cylinder to increasethe efficiency over that of the throttled spark-ignition engine bydecreasing pumping losses. In a traditional compression-ignition engine,ignition timing is controlled by the injection of diesel fuel into thecylinder near the end of the compression stroke, when the trapped airwithin the combustion chamber is of a sufficient temperature to ignitethe fuel. The heat released during the combustion process causes anincrease in in-cylinder pressure which then forces the piston downwardin the same fashion as the spark-ignition engine.

While more efficient than spark-ignition engines, compression-ignitionengines produce more of certain types of emissions which often requireexpensive aftertreatment. Consequently, it would be desirable to improvespark-ignition engines so as to control, minimize or otherwise preventthe occurrence of knock therein.

SUMMARY

One embodiment of the present invention is a unique system forcontrolling an operation of an engine. Other embodiments include uniquemethods, systems, devices, and apparatus to control, minimize orotherwise prevent the occurrence of knock within a spark-ignitionengine. Further embodiments, forms, objects, aspects, benefits,features, and advantages of the present invention shall become apparentfrom the figures and description provided herewith.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic view of an system incorporated within a vehicle.

FIG. 2 is a schematic view of an engine control system according to oneembodiment.

FIG. 3 is a partial schematic view of an engine according to oneembodiment.

FIG. 4 is a schematic view of the intake system shown in FIG. 1,according to one embodiment.

FIG. 5 is a partial schematic view of a engine control system accordingto another embodiment.

FIG. 6 is a schematic view of an embodiment of an exhaust system usagein embodiments of FIG. 2.

FIG. 7 is a schematic view of an embodiment of an exhaust gasrecirculation system usable in embodiments of FIG. 2.

FIGS. 8 to 11 are schematic views to certain embodiments of a fueldelivery system usable in embodiments of FIG. 2.

FIG. 12 is a schematic view of an alternate embodiment of an exhaust gasrecirculation system usable in embodiments of FIG. 2.

FIG. 13 is a schematic view of another alternate embodiment of anexhaust gas recirculation system usable in embodiments of FIG. 2.

FIG. 14 is a schematic view of a system for controlling aspects of anEGR system.

FIG. 15 is an schematic view of a controllable CAC system.

FIG. 16 is an schematic view of another embodiment of a controllable CACsystem.

FIG. 17 is an schematic view of another embodiment of a controllable CACsystem.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described embodiments, and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

FIG. 1 is a diagrammatic view of an engine 10 disposed within a vehicle11 having a fuel tank 12. Although the vehicle 11 is illustrated as amedium-duty truck, the vehicle 11 could alternatively be any of avariety of other vehicle types such as a light-duty or heavy-duty truck,semi-tractor, bus, car, SUV, motor coach, or different variety of landtraveling vehicle. In other embodiments, the vehicle 11 may be of amarine or aircraft type. In certain embodiments, the engine 10 isdisposed within an application that is not a vehicular application. Aswill be described in greater detail, an engine control system may beprovided to control, minimize or otherwise prevent the occurrence ofknock within the engine 10.

Referring to FIG. 2, an example engine control system 100 includes anengine 10 having an intake manifold 10 a and an exhaust manifold 10 b.In the illustrated embodiment, the engine control system 100 includes anintake system 102 fluidly coupled to the intake manifold 10 a, theintake system receiving compressed intake gases from a compressor 104.The example system 100 includes an EGR system 108 receiving exhaustgases through a first valve 109 a and/or through a second valve 109 b,and returning the exhaust gases to a position upstream of the compressor104. Any compressor 104, or each compressor, may be a directly poweredcompressor 104 (e.g. a supercharger), and/or a compressor side of aturbocharger (e.g. see the description referencing FIG. 5).

One of skill in the art will recognize the arrangement of the system 100as a low pressure EGR system 108. The low pressure EGR system 108provides for lower pumping losses relative to a high pressure EGR system(not shown), and further provides for a lower backpressure on the engineexhaust side, reducing residual gases in the cylinder and therebyreducing the tendency of the engine to experience knock. In certainembodiments, the EGR system 108 delivers the returned exhaust gasesdownstream of the compressor 104 (a high pressure EGR system), returnsthe exhaust gas to a position upstream of a first compressor anddownstream of a second compressor (not shown), or returns the exhaustgases to a position upstream of two compressors (not shown). The returnposition of the EGR system 108, in certain embodiments, is selectable bythe ECU 116, and the return position of the EGR system 108 is an exampleengine operational parameter controllable by the ECU 116 to reduce thelikelihood of engine knock.

The inlet position of the EGR system 108 may be at a position upstreamof the exhaust system 106, at a position downstream of the exhaustsystem 106, and/or at a position upstream of an exhaust throttle 114. Incertain embodiments, the exhaust throttle 114 is controllable, withoutlimitation, to provide back pressure and flow control for the EGR system108. In certain embodiments, the system 100 does not include an exhaustthrottle 114. The example system 100 illustrates the first valve 109 aas an EGR valve provided upstream of the EGR system 108. In certainembodiments, the first valve 109 a is provided downstream of the EGRsystem 108 but before the EGR flow returns to the inlet side of theengine 10. In certain embodiments, the first valve 109 a is omitted. Incertain embodiments, the second valve 109 b is provided downstream ofthe EGR system 108 but before the EGR flow returns to the inlet side ofthe engine 10. In certain embodiments, the second valve 109 b isomitted. In certain embodiments, the inlet position of the EGR system108 is selectable by the ECU 116, and the inlet position of the EGRsystem 108 is an example engine operational parameter controllable bythe ECU 116 to reduce the likelihood of engine knock.

In certain embodiments, the controller is structured to functionallyexecute the operations of the controller. The description hereinincluding the ECU 116 emphasizes the structural independence of theaspects of the ECU 116, and illustrates one grouping of operations andresponsibilities of the ECU 116. Other groupings that execute similaroverall operations are understood within the scope of the presentapplication. ECU 116 elements may be implemented in hardware and/or ascomputer instructions on a non-transient computer readable storagemedium, and ECU 116 elements may be distributed across various hardwareor computer based components.

Example and non-limiting ECU 116 implementation elements include sensorsproviding any value determined herein, sensors providing any value thatis a precursor to a value determined herein, datalink and/or networkhardware including communication chips, oscillating crystals,communication links, cables, twisted pair wiring, coaxial wiring,shielded wiring, transmitters, receivers, and/or transceivers, logiccircuits, hard-wired logic circuits, reconfigurable logic circuits in aparticular non-transient state configured according to the ECU 116specification, any actuator including at least an electrical, hydraulic,or pneumatic actuator, a solenoid, an op-amp, analog control elements(springs, filters, integrators, adders, dividers, gain elements), and/ordigital control elements.

The system 100 further includes a fuel delivery system 110 operationallycoupled to the engine 10. The fuel delivery system 110 includes any fueldelivery system 110 known in the art to deliver a fuel type usable bythe engine 10. Example fuel delivery systems 110 include a gasolinesystem with port fuel injection and/or direct injection, a gasoline anddiesel system with the gasoline deliverable by port fuel injectionand/or direct injection, a fuel delivery system 110 delivering astoichiometric fuel with port fuel injection and/or direct injection,and a fuel delivery system 110 delivering a stoichiometric fuel and acompression ignition fuel where the stoichiometric fuel is deliverableby port fuel injection and/or direct injection. As used herein, astoichiometric fuel is a fuel that is intended during normal operationto be combined with substantially a stoichiometric amount of oxygen,although non-stoichiometric formulations may be utilized in transient oreven extended operations. Without limitation, example oxygen amounts onthe low end of 80%, 90%, and 95% of stoichiometric, as well as exampleoxygen amounts of 105%, 110%, and 120% of stoichiometric on the highend, are substantially stoichiometric for certain applications.

The example system 100 further includes a variable valve timing (VVT)system 112. The components illustrated in the system 100 are example andnon-limiting, and various components may be present or omitted incertain embodiments.

The system 100 further includes an ECU 116. Generally, the ECU 116 iscommunicatively coupled to component of the engine control system 100.Example connections are illustrated in FIG. 2, although in any givenembodiment connections illustrated may not be present, and/or additionalconnections may be present. The ECU 116 forms a portion of a processingsubsystem including one or more computing devices having memory,processing, and communication hardware. The ECU 116 may be a singledevice or a distributed device, and the functions of the controller maybe performed by hardware or software.

The example, non-limiting, connections illustrated in FIG. 2 arerepresented by the dashed lines in FIG. 2. Arrows on the dashed linespointing away from the ECU 116 indicate that the ECU 116 is structuredto send control signals to the various components to control anoperation of the component. Arrows on the dashed lines pointing towardthe ECU 116 indicate that the ECU 116 is structured to receiveoperational signals from the various components indicating a parameterrelated to the operation of the component. Any illustrated connectionsmay additionally or alternatively be available to the ECU 116 over adatalink or network, or be provided to a memory location readable by theECU 116.

An example ECU 116 includes a processor (not shown) that is structuredto execute operating logic defining various control, management, and/orregulation functions. Such operating logic may be in the form ofdedicated hardware, such as a hardwired state machine, programminginstructions, and/or a different form as would occur to those skilled inthe art. The processor may be provided as a single component, or acollection of operatively coupled components; and may be comprised ofdigital circuitry, analog circuitry, or a hybrid combination of both ofthese types. When of a multi-component form, the processor may have oneor more components remotely located relative to the others. Theprocessor can include multiple processing units arranged to operateindependently, in a pipeline processing arrangement, in a parallelprocessing arrangement, and/or such different arrangement as would occurto those skilled in the art.

In certain embodiments, the processor is a programmable microprocessingdevice of a solid-state, integrated circuit type that includes one ormore processing units and memory. The processor can include one or moresignal conditioners, modulators, demodulators, Arithmetic Logic Units(ALUs), Central Processing Units (CPUs), limiters, oscillators, controlclocks, amplifiers, signal conditioners, filters, format converters,communication ports, clamps, delay devices, memory devices, and/ordifferent circuitry or functional components as would occur to thoseskilled in the art to perform the desired control, management, and/orregulation functions. The memory devices can be comprised of one or morecomponents and can be of any volatile or nonvolatile type, including thesolid state variety, the optical media variety, the magnetic variety,any combination of these, or such different arrangement as would occurto those skilled in the art. In one form, the processor includes acomputer network interface to facilitate communications using theController Area Network (CAN) standard among various components of theengine control system 100 and/or components not included in the depictedsystem, as desired.

In certain embodiments, the engine 10 is provided as a spark-ignitioninternal combustion engine, configured to develop mechanical power frominternal combustion of a stoichiometric mixture of fuel and inductiongas. As used herein, the phrase “induction gas” may include fresh air,recirculated exhaust gases, or the like, or any combination thereof. Theintake manifold 10 a receives induction gas from the intake system 102and distributes the induction gas to combustion chambers of the engine10. Accordingly, an inlet of the intake manifold 10 a is disposeddownstream of an outlet of the intake system 102, and an outlet of theintake manifold 10 a is disposed upstream of an inlet of each of thecombustion chambers in engine 10. The exhaust manifold 10 b collectsexhaust gases from combustion chambers of the engine 10 and conveys theexhaust gases to the exhaust system 106. Accordingly, an inlet of theexhaust manifold 10 b is disposed downstream of an outlet of each of thecombustion chambers in engine 10, and an inlet of the exhaust system106.

Referring to FIG. 3, the engine 10 may, for example, include a blockwith a cylinder 14 therein, and a piston 16 disposed within the cylinder14. The cylinder 14, the piston 16 and a cylinder head define acombustion chamber 18 for internal combustion of a mixture of inductiongas and fuel. Although FIG. 3 illustrates only one cylinder 14, piston16 and combustion chamber 18, it will be appreciated that the engine 10may include any number of cylinders, pistons and combustion chambers,which may all be of any size, and may operate according to any suitablespeeds and loads. The engine 10 may further include an intake valve 20 aand an exhaust valve 20 b associated with each cylinder 14.

In one embodiment, the intake valve 20 a can be controllably movedbetween open and closed positions (e.g., under control of the VVT system112) to control the flow of induction gas into the combustion chamber 18from the intake manifold 10 a. In another embodiment, the exhaust valve20 b can be controllably moved between open and closed positions (e.g.,under control of the VVT system 112) to control the flow of exhaust gasfrom the combustion chamber 18 to the exhaust manifold 10 b. FIG. 3illustrates the valves 20 a, 20 b under control of the VVT system 112,although in certain embodiments a non-variable valve timing system (notshown) is contemplated. Although FIG. 3 illustrates only one intakevalve 20 a and one exhaust valve 20 b associated with the combustionchamber 18, it will be appreciated that any number of intake valves 20 aand exhaust valves 20 b may be associated with any combustion chamber18. The example engine 10 further includes an ignition source such asspark plug 22 (or plugs). Although not shown, injectors may also bearranged within the engine 10 to deliver fuel directly into thecombustion chamber 18. Referring back to FIG. 2, an improvement inengine knock management capability allows the engine 10 to operate athigher cylinder pressures providing for higher BMEP and allowing higheramounts of exhaust gas recirculation.

The intake system 102 is structured to adjust a temperature of theinduction gas delivered to the engine 10. In one embodiment, the intakesystem 102 can be structured to lower or raise the temperature ofinduction gas delivered to the intake manifold 10 a. As exemplarilyillustrated, an inlet of the intake system 102 is disposed downstream ofan outlet of the compressor 104 and an outlet of the intake system 102is disposed upstream of the intake manifold 10 a.

Referring to FIG. 4, an example intake system 102 shown in FIG. 2includes an charge air cooler bypass valve 202, a charge air cooler 204,a charge air cooler bypass circuit 206, and an intake air throttle 208.The charge air cooler 204 may be provided as an air-to-air cooler, aliquid-to-air cooler, or the like, and can be configured in any suitablemanner. The intake air throttle 208 is configured to control the amountof induction gas flowing to the engine 10. The illustrated position ofthe intake air throttle 208 is a non-limiting example.

As exemplarily illustrated, the charge air cooler bypass valve 202 isstructured to receive induction gas output from the compressor 104 andredirect the induction gas to the charge air cooler 204, to the chargeair cooler bypass circuit 206, or a combination thereof. By redirectingthe induction gas as described above, the temperature of the inductiongas delivered to the engine 10 can be adjusted. In one embodiment, thecharge air cooler bypass valve 202 is provided as a three port valvehaving a rotor that can be actuated (e.g., under control of ECU 116) toselectively place the inlet of the charge air cooler 204 or the chargeair cooler bypass circuit 206 in fluid communication with the outlet ofthe compressor 104. In another embodiment, the charge air cooler bypassvalve 202 can be actuated to adjust a ratio of induction gas flow intothe charge air cooler 204 to induction gas flow into the charge aircooler bypass circuit 206. Although the charge air cooler bypass valve202 has been described as a three port valve, it will be appreciatedthat the charge air cooler bypass valve 202 may be provided as any othersuitable valve, or system of valves, enabling the selective redirectionof induction gas among the charge air cooler 204 and the charge aircooler bypass circuit 206.

In an alternative embodiment, the charge air cooler bypass valve 202 maybe replaced by an orifice or other restriction within a conduitconveying induction gas from the compressor 104. In yet anotherembodiment, the charge air cooler bypass valve 202 may be removed,providing a substantially unobstructed branch between conduits conveyinginduction gas to the inlets of the charge air cooler 204 and the chargeair cooler bypass circuit 206.

As exemplarily illustrated, the charge air cooler bypass valve 202 isdisposed upstream of the inlet of the charge air cooler 204, andupstream of the charge air cooler bypass circuit 206. In anotherembodiment, however, the charge air cooler bypass valve 202 can bedisposed downstream of an outlet of the charge air cooler 204,downstream of the charge air cooler bypass circuit 206 and upstream ofan inlet of the intake air throttle 208.

The charge air cooler 204 and charge air cooler bypass valve 202 areillustrated as downstream of a single compressor 104. In certainembodiments, the system 100 includes multiple compressors, and thecharge air cooler 204 and charge air cooler bypass valve 202 may bepositioned between the compressors, and/or downstream of all of thecompressors. Additionally or alternatively, one or more compressors mayeach include a charge air cooler and charge air cooler bypass valve. Theposition of any charge air cooler bypass valve 202 is an example engineoperational parameter controllable by the ECU 116 to reduce thelikelihood of engine knock.

Referring back to FIG. 2, the compressor 104 is configured to compressinduction gas such as fresh air from outside the engine control system100, recirculated exhaust gas from the EGR system 108, or any othersuitable oxidant from another source (not shown). In one embodiment, thecompressor 104 may be provided as a centrifugal compressor. In anotherembodiment, the compressor 104 can be provided as a supercharger, whichis driven by a belt, gear, shaft, chain, or the like or any combinationthereof, connected to a crankshaft (not shown) of the engine 10. Asexemplarily illustrated, an inlet of the compressor 104 is disposeddownstream of an outlet of a fresh air intake (not shown) and downstreamof an outlet of the EGR system 108.

Referring to FIG. 5, in another embodiment, the compressor 104 may beprovided as a component of a turbocharger. For example, the system 100may further include a turbine 118 disposed at an outlet of the exhaustmanifold 10 b and mechanically coupled to the compressor 104 by a shaft,rod, or the like, thus forming the turbocharger. In one embodiment, theturbocharger may be provided as a variable geometry turbocharger capableof improving turbocharger efficiency over the entire engine map and,therefore, improving pumping efficiency. It will be appreciated,however, that the turbocharger may be provided in any other suitablemanner (e.g., as a multi-stage turbocharger, or the like), and may beprovided with or without a wastegate and/or bypass. The illustration inFIG. 5 shows the first valve 109 a downstream of the turbine 118, in alow pressure EGR configuration.

Referring back to FIG. 2, an example exhaust system 106 is structured toreduce emissions from exhaust gas generated by the engine 10. Theexhaust system 106 includes any aftertreatment components known in theart. Example aftertreatment components treat carbon monoxide (CO),unburned hydrocarbons (HC), nitrogen oxides (NO_(x)), volatile organiccompounds (VOC), and/or particulate matter (PM). As exemplarilyillustrated, an inlet of the exhaust system 106 is disposed downstreamof an outlet of the exhaust manifold 10 b.

Referring to FIG. 6, one embodiment of the exhaust system 106 includes aparticulate filter (PF) 302 disposed upstream of a catalytic converter304 such as a three-way catalytic converter (TWC). The particulatefilter 302 is structured to remove particulate matter such ascarbon-based particulates, for example including soot, from the exhaustgas generated by the engine 10. The example catalytic converter 304 isstructured to reduce nitrogen oxides to nitrogen and oxygen, oxidizecarbon monoxide to carbon dioxide, and/or oxidize unburned hydrocarbonsto carbon dioxide and water. The particulate filter 302 and catalyticconverter 304 can be combined into a single housing (as illustrated) orcan be provided in separate housings fluidly coupled by a conduit.

In certain embodiments, the particulate filter 302 requires periodic orintermittent regeneration, for example to oxidize trapped particles inthe particulate filter 302. Regeneration of an example particulatefilter 302 requires an elevated temperature, which may in certainoperating conditions be readily available due to normal engineoperations and in certain operating conditions may not be availablewithout adjustment to normal engine operations. In certain embodiments,the catalytic converter 304 requires certain exhaust gas conditions toproperly operate and/or regenerate. An example catalytic converter 304requires continuous, periodic, and/or intermittent stoichiometric orrich conditions in the engine exhaust gases. The regeneration andoperating conditions for the particulate filter 302 and catalyticconverter 304 described herein are non-limiting examples.

Referring to FIG. 7, one embodiment of the EGR system 108 shown in FIG.2 includes an EGR cooler bypass valve 402, an EGR cooler 404, an EGRcooler bypass circuit 406, and an EGR valve 408. The EGR cooler 404 maybe provided as an air-to-air cooler, a liquid-to-air cooler, or thelike, and can be configured in any suitable manner. The EGR cooler 404is structured to exchange heat between the coolant (air, engine coolant,etc.) and the EGR gas flowing through the EGR cooler 404. The positionof the EGR bypass valve 402 is an example engine operational parametercontrollable by the ECU 116 to reduce the likelihood of engine knock.

In certain additional or alternative embodiments to the EGR system 108of FIG. 7, a coolant flow rate through the EGR cooler 404 iscontrollable by the ECU 116. Accordingly, a heat transfer rate withinthe EGR cooler 404 is controllable by the coolant flow rate. The coolantflow rate through the EGR cooler 404 is an example engine operationalparameter controllable by the ECU 116 to reduce the likelihood of engineknock.

A system 100 including the charge air cooler bypass circuit 206 and theEGR cooler bypass circuit 406 permit the ECU 116 to reduce thetemperature of induction gases at the intake manifold 10 a in a flexiblemanner. The EGR cooler bypass circuit 406 permits the ECU 116 tocontinue to flow EGR at temperatures below the EGR condensation limit inapplications where otherwise condensation would be destructive to, orreduce the service life of, the EGR cooler. The charge air cooler bypasscircuit 206 and the EGR cooler bypass circuit 406 also allow the ECU 116to advantageously utilize off-nominal high or low temperatures thatoccur, for example due to engine warm-up conditions and/oraftertreatment thermal management operations. The EGR valve 408, wherepresent, is structured to control the amount of exhaust gas thatrecirculates.

As exemplarily illustrated, the EGR cooler bypass valve 402 isconfigured to receive exhaust gas output from the exhaust manifold 10 b,the exhaust system 106, or a combination thereof, and redirect theexhaust gas to the EGR cooler 404, to the EGR cooler bypass circuit 406,or a combination thereof. By redirecting the exhaust gas as describedabove, the temperature of the recirculated exhaust gas delivered to theinlet of the compressor 104 can be adjusted. In one embodiment, the EGRcooler bypass valve 402 is provided as a three port valve having a rotorthat can be actuated (e.g., under control of ECU 116) to selectivelyplace the inlet of the EGR cooler 404 or the EGR cooler bypass circuit406 in fluid communication with the outlet of the exhaust manifold 10 b,the outlet of the exhaust system 106, or a combination thereof.

In certain embodiments, the EGR cooler bypass valve 402 can be actuatedto adjust a ratio of exhaust gas flow into the EGR cooler 404 to exhaustgas flow into the EGR cooler bypass circuit 406. Although the EGR coolerbypass valve 402 has been described as a three port valve, it will beappreciated that the EGR cooler bypass valve 402 may be provided as anyother suitable valve, or system of valves, enabling the selectiveredirection of exhaust gas among the EGR cooler 404 and the EGR coolerbypass circuit 406. In an alternative embodiment, the EGR cooler bypassvalve 402 may be replaced by an orifice or other restriction within oneor more conduits conveying exhaust gas from the exhaust manifold 10 b,the exhaust system 106, or a combination thereof. In yet anotherembodiment, the EGR cooler bypass valve 402 may be removed, providing asubstantially unobstructed branch between conduits conveying exhaust gasto the inlets of the EGR cooler 404 and the EGR cooler bypass circuit406.

As exemplarily illustrated, the EGR cooler bypass valve 402 is disposedupstream of the inlet of the EGR cooler 404, and upstream of the EGRcooler bypass circuit 406. In another embodiment, however, the EGRcooler bypass valve 402 can be disposed downstream of an outlet of theEGR cooler 404 and downstream of the EGR cooler bypass circuit 406.

In one embodiment, the EGR valve 408 is provided as a two port valvethat can be actuated (e.g., under control of ECU 116) to control thevolume of exhaust gas that is recirculated to the inlet of thecompressor 104. As exemplarily illustrated, the EGR valve 408 isdisposed downstream of the outlet of the EGR cooler 404, and downstreamof the EGR cooler bypass circuit 406. In another embodiment, however,the EGR valve 408 can be disposed upstream of an inlet of the EGR cooler404 and upstream of the EGR cooler bypass circuit 406.

Referencing FIG. 12, an example EGR system 108 is illustrated. The EGRsystem 108 includes a first EGR coolant provider 1202 and a second EGRcoolant provider 1204. The first EGR coolant provider is a hightemperature cooling loop 1206 providing high temperature coolant to theEGR cooler 404, and the second EGR coolant provider is a low temperaturecooling loop 1208 providing low temperature coolant to the EGR cooler404. The providing of high temperature and low temperature coolantincludes any means understood in the art to provide a high or lowtemperature coolant.

Without limitation, an example first EGR coolant provider 1202 includesengine coolant, a heated gas stream available in the system 100 (e.g.compressed air from a compressor 104 stage), or any other coolantavailable in the system. Without limitation, an example second EGRcoolant provider 1204 includes any coolant source that, at least duringcertain engine operating conditions, tends to be a lower temperaturecoolant than the coolant provided by the first EGR coolant provider1202. Example and non-limiting low temperature coolant sources includeengine coolant having a longer fluid run than the high temperaturecoolant (e.g. where the low temperature cooling loop 1208 is longer thanthe high temperature cooling loop 1206), ambient air, and/or a dedicatedlower temperature coolant provided for the second EGR coolant provider1204.

The coolant temperatures that are a high coolant temperature and a lowcoolant temperature are relative only, and no absolute temperatureranges defining a high coolant temperature or low coolant temperatureare required. An example system 100 includes a high coolant temperatureof about 90° C. and a low coolant temperature of about 60° C., althoughany temperatures of a coolant available in the system 100 arecontemplated herein. Regardless of the temperature difference betweenthe high coolant temperature and the low coolant temperature, the ECU116 is structured, in certain embodiments, to provide the hightemperature coolant, low temperature coolant, or a selectable mixturethereof, to the EGR cooler 404 to control the outlet temperature of theEGR gas. Any temperature difference between the high temperature coolantand the low temperature coolant, even where the difference is onlypresent at certain engine operating conditions, provides a controlelement for the ECU 116 to adjust the temperature of the EGR gas. Anexample EGR system 108 includes a high temperature coolant valve 1210and/or a low temperature coolant valve 1212. The position of any hightemperature coolant valve 1210 and/or low temperature coolant valve 1212is an example engine operational parameter controllable by the ECU 116to reduce the likelihood of engine knock.

Referencing FIG. 13, an example EGR system 108 is illustrated. Theexample EGR system 108 includes a first EGR cooler 404 and a second EGRcooler. The EGR coolers 404, 1302, at least in certain engine operatingconditions, provide discrete EGR cooling capabilities. The discrete EGRcooling capabilities can be provided by any means understood in the art,including at least a differential coolant temperature for a coolantcorresponding to each EGR cooler 404, 1302, a differential effectivethermal contact area within each EGR cooler 404, 1302, and/or adifferential coolant flow rate within each EGR cooler 404, 1302. Themagnitude of any differential between the discrete EGR coolingcapabilities is not an important consideration, as long as at leastduring certain engine operating conditions a significant coolingcapability difference exists between the EGR cooler 404, 1302. A minimumvalue for a significant cooling capability is a difference that exceedsthe calibration or measurement error or variability. In certainembodiments, a significant cooling capability difference is greater than25% difference, and/or greater than 50% difference, during certainoperating conditions of the engine. Any cooling capability differencebetween the first EGR cooler 404 and the second EGR cooler 1302, evenwhere the difference is only present at certain engine operatingconditions, provides a control element for the ECU 116 to adjust thetemperature of the EGR gas. An example EGR system 108 includes the EGRcooler bypass valve 402 (or valves) capable of providing continuously ordiscretely selectable flow fractions to the EGR cooler bypass circuit406, the first EGR cooler 404, and/or the second EGR cooler 1302. Theposition of any EGR cooler bypass valve(s) 402, and/or the flowfractions through the EGR bypass circuit 406 and/or coolers 404, 1302,are example engine operational parameters controllable by the ECU 116 toreduce the likelihood of engine knock.

In certain embodiments, the EGR system 108 includes an EGR temperatureadjustment device. Example and non-limiting EGR temperature adjustmentdevices include the EGR cooler bypass valve 402, a high temperaturecoolant valve 1210, and/or a low temperature coolant valve 1212. Anyother devices known in the art to provide capability to adjust EGRtemperatures are also contemplated herein, for example an EGR coolantflow actuator associated with a single coolant flow on a single EGRcooler (not shown).

Referring back to FIG. 2, the fuel delivery system 110 is structured todeliver fuel to the engine 10. Although not shown, the fuel deliverysystem 110 includes the fuel tank 12 shown in FIG. 1. In one embodiment,the fuel delivery system 110 can be configured to deliver gasoline tothe engine 10. In another embodiment, the fuel delivery system 110 canbe configured to deliver another type of fuel, in addition to gasoline,to the engine 10. Examples of such additional fuels include diesel (orother high cetin fuels), natural gas, ethanol, and the like. In oneembodiment, the fuel delivery system may include one or more injectorsconfigured to inject fuel into the engine 10 so that it may be combustedwithin a combustion chamber. Example injectors include direct injectorsand port injectors. Example embodiments of the fuel delivery system 110are described below with respect to FIGS. 8 to 11.

Referring to FIG. 8, one embodiment of the fuel delivery system 110shown in FIG. 2 includes a first tank 502, a second tank 504, a firstinjector 506 and a second injector 508. Together, the first tank 502 andthe second tank 504 constitute a system that can be described as theaforementioned fuel tank 12. The first tank 502 and the second tank 504can be configured to retain a fuel such as gasoline, diesel, naturalgas, ethanol, or the like. In one embodiment, the first tank 502 and thesecond tank 504 are configured to retain different fuels. For example,the first tank 502 can retain a first fuel such as gasoline and thesecond tank 504 can retain a second fuel such as diesel. As exemplarilyillustrated, an outlet of the first tank 502 is disposed upstream of aninlet of the first injector 506 and an outlet of the second tank 504 isdisposed upstream of an inlet of the second injector 508.

The first injector 506 and the second injector 508 can be provided asany type of injector suitable for injecting fuel (e.g., under control ofECU 116) into the engine 10 so that fuel can be combusted within acombustion chamber therein. The first injector 506 and the secondinjector 508 may be provided as the same type of injectors, but arrangedat different locations relative to a combustion chamber, or they may beprovided as different injectors. For example, the first injector 506 maybe provided as a direct injector and the second injector 508 may beprovided as a port injector. In another example, the first injector 506and the second injector 508 may both be provided as direct injectors orport injectors. In one embodiment, use of a direct injector can improvein-cylinder charge temperatures to minimize the occurrence of knock. Adirect injector can also improve engine and after-treatment warm-up toallow quick engine operation at optimal efficiency. In one embodiment,use of multiple injectors (e.g., a direct injector and a port injector)can create multiple sources of ignition of fuel, allowing for fastcombustion rates. Use of multiple injectors also creates large amountsof ignition energy, which can ignite dilute mixtures at high cylinderpressures. As exemplarily illustrated, the first injector 506 isconfigured to inject fuel retained within first tank 502 and the secondinjector 508 is configured to inject fuel retained within second tank504.

Referring to FIG. 9, a fuel delivery system 110 according to anotherembodiment includes the aforementioned first tank 502 and the secondtank 504, and further includes a fuel delivery valve 510 and an injector512. The first tank 502 and the second tank 504 may be provided asexemplarily described above with respect to FIG. 8. The injector 512 maybe provided as a direct injector or as a port injector.

In the illustrative example, the fuel delivery valve 510 is configuredto receive fuel from the first tank 502, the second tank 504, or acombination thereof, and pass the fuel to the injector 512. In oneembodiment, the fuel delivery valve 510 is provided as a three portvalve having a rotor that can be actuated (e.g., under control of ECU116) to selectively place the inlet of the injector 512 in fluidcommunication with the outlet of the first tank 502 or the outlet of thesecond tank 504. In another embodiment, the fuel delivery valve 510 canbe actuated to adjust a ratio of fuel conveyed from the first tank 502to fuel conveyed from the second tank 504.

Referring to FIG. 10, a fuel delivery system 110 according to yetanother embodiment includes the aforementioned first tank 502, secondtank 504, first injector 506, second injector 508 and fuel deliveryvalve 510, and further includes an additional fuel delivery valve 514.The first tank 502, second tank 504, first injector 506 and secondinjector 508 may be provided as exemplarily described above with respectto FIG. 8. Likewise, the fuel delivery valve 510 may be provided asexemplarily described above with respect to FIG. 9.

The additional fuel delivery valve 514 may be provided in a similarmanner as the fuel delivery valve 510. For example, the additional fueldelivery valve 514 is configured to receive fuel from the first tank502, the second tank 504, or a combination thereof, and pass the fuel tothe second injector 508. In one embodiment, the additional fuel deliveryvalve 514 is provided as a three port valve having a rotor that can beactuated (e.g., under control of ECU 116) to selectively place the inletof the second injector 508 in fluid communication with the outlet of thefirst tank 502 or the outlet of the second tank 504. In anotherembodiment, the additional fuel delivery valve 514 can be actuated toadjust a ratio of fuel conveyed from the first tank 502 to fuel conveyedfrom the second tank 504.

Referring to FIG. 11, a fuel delivery system 110 according to stillanother embodiment includes the aforementioned first injector 506 andsecond injector 508, and further includes a single tank such as tank 12and a fuel delivery valve 516. The first injector 506 and secondinjector 508 may be provided as exemplarily described above with respectto FIG. 8. The fuel delivery valve 516 may be configured to receive fuelfrom the tank 12 and pass the fuel to the first injector 506, the secondinjector 508, or a combination thereof In one embodiment, the fueldelivery valve 516 is provided as a three port valve having a rotor thatcan be actuated (e.g., under control of ECU 116) to selectively placethe inlet of the first injector 506 or the second injector 508 in fluidcommunication with the outlet of the tank 12. In another embodiment, thefuel delivery valve 516 can be actuated to adjust a ratio of fuelconveyed to the first injector 506 to fuel conveyed to the secondinjector 508.

The selection of fuel sources and/or fuel delivery valve 516 positionsare example engine operational parameters controllable by the ECU 116 toreduce the likelihood of engine knock. For example and withoutlimitation, an example ECU 116 is structured to adjust a fuel type, aratio of fuel types, an injection type (e.g. homogenous mixture vs.direct injection), and/or a ratio of injection types at certain engineoperating conditions to reduce the likelihood of engine knock.

Referring back to FIG. 2, the VVT system 112 is structured to adjust(e.g., under control of the ECU 116) the opening and closing of one ormore intake valves 20 a and one or more exhaust valves 20 b associatedwith one or more cylinders 14 of the engine 10. As described herein, theVVT system 112 refers to any mechanism that can change the lift,duration and/or timing of intake valves 20 a and exhaust valves 20 bduring operation of the engine 10. The VVT system 112 can be provided asany suitable mechanical device (camless or otherwise), electro-hydraulicdevice, or the like, or a combination thereof. In one embodiment, theVVT system 112 is provided as a dual independent cam phasing system. Inone embodiment, the VVT system 112 can be controlled to improve knockmargin by changing valve overlap to reduce residual cylinder gasesand/or increase pumping efficiency. As used herein, the term “valveoverlap” refers to a period of time in an engine cycle during which theintake valve 20 a and the exhaust valve 20 b of a particular cylinder 14are simultaneously open. Thus an “amount” of valve overlap refers to theamount of time during which the intake valve 20 a and the exhaust valve20 b of a particular cylinder 14 are simultaneously open. The adjustmentof engine valve timing by control of the VVT system 112 an exampleengine operational parameter controllable by the ECU 116 to reduce thelikelihood of engine knock.

As mentioned above the exhaust system 106 may, in one embodiment,include a particulate filter 302 disposed upstream of a catalyticconverter 304. With the passage of time during engine operation,particulate matter can build up in the particulate filter 302 to thatpoint that further accumulation may threaten to degrade filtrationand/or undesirably restrict the flow of exhaust through the exhaustsystem 106. Therefore, it can be beneficial to remove the particles byoxidation, through a process known as regeneration.

In one embodiment, the VVT system 112 can be configured to regenerate(e.g., under control of the ECU 116) and/or promote regeneration of theparticulate filter 302. For example, the particulate filter 302 can beregenerated by controlling the VVT system 112 to increase the amount ofvalve overlap from a first amount of valve overlap to a second amount ofvalve overlap. The first amount of valve overlap may be the amount ofvalve overlap employed when no knock event is occurring within theengine 10. Upon increasing the amount of valve overlap, the amountand/or rate of induction gas flowing from the intake manifold 10 a tothe exhaust manifold 10 b (i.e., scavenging) can be increased. Excessoxygen in the induction gas delivered to the exhaust system 106 isreacted with the particulate matter in the particulate filter 302,allowing the catalytic converter 304 to operate without excess oxygen toeffectively reduce NOR.

In certain embodiments, a device is actuated to restrict, reduce, orotherwise prevent exhaust gas from being recirculated to the inlet ofthe compressor 104, for example a component of the EGR system 108 (e.g.,the EGR valve 408), the first valve 109 a, and/or second valve 109 b canbe actuated. Any of the devices to restrict, reduce, or prevent exhaustgas from being recirculated may be under the control of the ECU 116.When the EGR is reduced, restricted, or prevented, the oxygen content ofthe induction gas delivered to the intake manifold 10 a can be modulatedor increased.

In one embodiment, the particulate filter 302 can be regeneratedperiodically, on the basis of a particulate load in the particulatefilter 302, a temperature of the particulate filter 302, or the like ora combination thereof. The particulate filter 302 is regeneratedperiodically by providing a sufficiently high exhaust gas temperature,and/or by utilizing an already provided sufficiently high exhaust gastemperature, and further by providing sufficient oxygen or oxidizingconstituents (e.g. NO₂) in the exhaust gas to support the particulatefilter 302 regeneration. In certain embodiments, excess oxygen oroxidizing constituents are provided at a low enough level such that theparticulate filter 302 is regenerated, but that the catalytic converter304 continues to operate normally. In certain embodiments, the catalyticconverter 304 is capable to operate lean, and/or the operations of thecatalytic converter 304 are not required at all times and theregeneration of the particulate filter 302 is prioritized at certaintimes and operating conditions.

The exhaust throttle 114 is configured to adjust (e.g., under control ofthe ECU 116) the rate with which exhaust gas is expelled from the enginecontrol system 100. The exhaust throttle 114 is an optional componentwithin the engine control system 100 and may be omitted. In certainembodiments, the exhaust throttle 114 is provided and controllable (e.g.by the ECU 116) to promote flow of EGR and/or to reduce a total gas flowrate through the system 100. In certain embodiments, the position of theexhaust throttle 114 is an example engine operational parametercontrollable by the ECU 116 to reduce the likelihood of engine knock.

Additionally or alternatively to the depicted embodiment of FIG. 2, anintake throttle (not shown) may be provided upstream of the compressor104. In certain embodiments, the intake throttle (not shown) may beprovided upstream of one or both of two compressors present in thesystem 100. The intake throttle is an optional component within theengine control system 100 and may be omitted. In certain embodiments,the intake throttle is provided and controllable (e.g. by the ECU 116)to promote the flow of EGR and/or to reduce a total gas flow ratethrough the system 100. In certain embodiments, the position of theintake throttle is an example engine operational parameter controllableby the ECU 116 to reduce the likelihood of engine knock.

In certain embodiments, the ECU 116 is structured to detect and/orinterpret one or more parameters related to the operation of the engine10, to determine a knock index value in response to the one or moredetected parameters, and to compare the knock index value with a knockthreshold value. The knock index value is an incremental indicator ofthe risk of knock during a combustion event, and may be correlated witha modeled or measured knock probability, a knock measurement device, asound threshold, an in-cylinder measurement installed in a test engine,and/or any other indicator of knock understood in the art. The knockthreshold value is a selected threshold for the indicator of the risk ofknock according to the selected indication method. The selection ofunits for the knock index value, or the selection of a magnitude scalefor a dimensionless knock index value, are mechanical steps for one ofskill in the art having the benefit of the disclosure herein. In certainembodiments, a quantitative or qualitative knock description isdeveloped for a test engine, the values of the knock index value arecalibrated to the selected parameters related to the engine, and theknock threshold value is set according to the desired knock thresholdvalue and/or the desired knock threshold value with a margin applied.

In certain embodiments, the knock threshold value changes over time,with engine operating conditions, according to operator inputs, oraccording to other selected criteria. Example and non-limitingoperations to adjust the knock threshold value include raising orlowering the knock threshold value as the engine ages, increasing theknock threshold value as the engine load increases, and/or increasingthe knock threshold value in response to an operator request for greaterresponse or power output.

The ECU 116 is structured to interpret the parameter(s) related to theoperation of the engine 10. Certain operations described herein includeoperations to interpret one or more parameters. Interpreting, asutilized herein, includes receiving values by any method known in theart, including at least receiving values from a datalink or networkcommunication, receiving an electronic signal (e.g. a voltage,frequency, current, or PWM signal) indicative of the value, receiving asoftware parameter indicative of the value, reading the value from amemory location on a computer readable medium, receiving the value as arun-time parameter by any means known in the art, and/or by receiving avalue by which the interpreted parameter can be calculated, and/or byreferencing a default value that is interpreted to be the parametervalue. The ECU 116 communicates with any sensor, actuator, datalink,network, or other device in the system 100 according to the selectedparameters for a given embodiment.

Example parameters related to the operation of the engine 10 include anyparameters that affect or can be correlated to the occurrence of knock.Example and non-limiting parameters related to the operation of theengine 10 include an induction gas temperature at the intake system 102,an induction gas temperature at the intake manifold 10 a, an inductiongas pressure at the intake manifold 10 a, an exhaust gas temperature atthe exhaust manifold 10 b, an exhaust gas pressure at the exhaustmanifold 10 b, an exhaust gas temperature at the inlet and/or outlet ofthe exhaust system 106, an exhaust gas pressure at the inlet and/oroutlet of the exhaust system 106, an exhaust gas temperature at theinlet and/or outlet of the EGR system 108, an exhaust gas pressure atthe inlet and/or outlet of the EGR system 108, a lift, duration and/ortiming of an intake valve 20 a and/or an exhaust valve 20 b, a rate offuel injection, a type of fuel injected, a speed of compressor 104, ageometry or position of the turbine 118, a composition of induction gasand/or EGR gas, an engine speed value, an engine load, engine torque,engine power output value, and/or combinations thereof. Additionally oralternatively, an example parameter includes a rate of change or othertransformation of any described parameter. The illustrative parametersare example and non-limiting.

In response to the ECU 116 determining that the knock index valueexceeds the knock threshold value, the ECU 116 is structured to controlan operation of one or more of the components of the engine controlsystem 100 shown in FIGS. 2 to 11 to decrease a likelihood of knockoccurring. In certain embodiments, the ECU 116 provides an enginecontrol command, and one or more components of the engine control system100 are responsive to the engine control command. The engine controlcommand, in certain embodiments, includes one or more messages, and/orincludes one or more parameters structured to provide instructions tothe various engine components responsive to the engine control command.An engine component responding to the engine control command may followthe command, receive the command as a competing instruction with othercommand inputs, utilize the command as a target value or a limit value,and/or progress in a controlled manner toward a response consistent withthe engine control command.

The operation to decrease the likelihood of knock occurring may or maynot decrease the knock index value. For example, an example knock indexvalue is based on an engine torque output value, and the ECU 116 reducesa temperature of the EGR gas flow in response to the knock index valueexceeding the knock threshold value. The reduction of the EGR gas flowtemperature does not directly decrease the correlated parameter for theknock index value (the engine torque output value), and accordingly thedetermined knock index value remains high although the likelihood ofengine knock is reduced.

In certain embodiments, the ECU 116 is structured to detect and/orinterpret one or more parameters that affect or that can be correlatedto operation of the particulate filter 302, and to determine whether aparticulate filter regeneration is indicated in response to theparameter(s) that affect or can be correlated to operation of theparticulate filter 302. Example and non-limiting parameters that affector can be correlated to operation of the particulate filter 302 includea flow rate through the particulate filter 302, a pressure drop acrossthe particulate filter 302, a pressure at a position upstream of theparticulate filter 302, a temperature of exhaust gases flowing throughthe particulate filter 302, a viscosity of exhaust gases flowing throughthe particulate filter 302, a temperature of the substrate of theparticulate filter 302, estimated or measured particulate emissions ofthe engine 10, and/or a composition of the exhaust gas passing throughthe particulate filter 302. The determination of a particulate filter302 loading and/or an indication for a particulate filter regenerationare mechanical steps for one of skill in the art.

In response to the ECU 116 determining the particulate filterregeneration is indicated, an example ECU 116 controls an operation ofthe VVT system 112 to regenerate and/or support regeneration of theparticulate filter 302. Example operations of the VVT system 112 includeoperations to raise a temperature of exhaust gases from the engine 10(e.g. earlier opening of exhaust valves), and/or an operation to enhancean oxygen content of the exhaust gases from the engine 10 (e.g. bypassing compressed intake air out of a delayed closing exhaust valve).Any operations of the VVT system 112 to regenerate and/or supportregeneration of the particulate filter 302 are contemplated herein. Anexample ECU 116 is structured to control the fuel delivery system 110 tooperate one or more cylinders at a lean condition to increase thetemperature and/or available oxygen to regenerate and/or supportregeneration of the particulate filter 302.

Referencing FIG. 14, an example system 1400 is illustrated forcontrolling an EGR flow rate, EGR temperature, and/or an intake manifoldtemperature. The system 1400 includes an aftertreatment component,depicted in the example as a three-way catalyst 304 (TWC), and a numberof control valves 1402, 1404, 1406. A first control valve 1402 providesfor EGR recirculation upstream of the TWC 304. A second control valve1404 provides for EGR recirculation at an intermediate position withinthe TWC 304. The third control valve 1406 provides for EGR recirculationat a position downstream of the TWC 304. One of skill in the art willrecognize that, generally, the more downstream EGR recirculationpositions are at a lower pressure from the resulting pressure drop inthe TWC 304 and at a lower temperature due to increased heat transferlosses due to residence time in the aftertreatment systems.

Accordingly, in a typical embodiment, changing EGR recirculationpositions toward the downstream position (e.g. from the second controlvalve 1404 to the third control valve 1406) results in a reduced EGRflow rate, reduced EGR temperature, and/or reduced intake manifoldtemperature. Conversely, changing EGR recirculation positions toward theupstream position results in an increased EGR flow rate, increased EGRtemperature, and/or increased intake manifold temperature. However, incertain embodiments the activity on the aftertreatment component and/orthe composition of the exhaust gases may provide for a reversal in oneor more of the behaviors from the typical embodiment. For example, andwithout limitation, where the aftertreatment component includes anoxidation catalyst, a temperature rise across the aftertreatmentcomponent, providing for a reduced EGR temperature when the EGRrecirculation position is moved to a more upstream position.

The provided control valves 1402, 1404, 1406 are non-limiting examples.In certain embodiments, one or more valves 1402, 1404, 1406 may bemissing, and one or more valves not shown may be present. In certainembodiments, more than one valve at more than one intermediate positionwithin the aftertreatment component may be provided. The stream 1408 isan exhaust stream from the engine, which may be at a position downstreamof one or more turbines, and/or downstream of one or more aftertreatmentcomponents which are not depicted. The stream 1410 is an EGR streamwhich may return to any position in the system, including to a positionupstream or downstream of one or more compressors, charge coolers, orother system components. The stream 1412 is an exhaust stream, which mayexit the system, and/or pass to a turbine, exhaust valve, aftertreatmentcomponent, or any other component. The routing of the EGR stream 1410,for example with the effluents of the control valves 1402, 1404, 1406being combined, is a non-limiting depiction. The effluents of thecontrol valves 1402, 1404, 1406 may not be combined, and may be routedto the same or distinct positions in the engine intake system.Additionally, other EGR streams may be present in the system 1402 (notshown).

The ECU 116 may operate the control valves 1402, 1404, 1406. In oneexample, the ECU 116 controls one or more of an EGR temperature, EGRflow rate, and/or intake manifold temperature, where the controloperations include operating the control valves 1402, 1404, 1406.

Referencing FIG. 15, an example controllable charge air cooler system1500 is depicted. The system 1500 includes a charge air cooler 1512(CAC) which may be an air-to-air or coolant based system. The coolantbased system, where present, may share coolant with the engine coolant,and/or may be a separate or dedicated coolant system. Additionally oralternatively, a temperature of the coolant in the coolant based systemmay be separate from the engine coolant temperature, either through acontrollable mechanism, the use of an auxiliary radiator, or throughother means. An air-to-air coolant system generally uses ambient air asis known in the art. The system 1500 depicts an uncooled intake air1506, the cooled intake air 1508, and a downstream coolant stream 1504.

The system 1500 schematically depicts a control valve 1510, which mayinclude one or more physical valves of any type, that provide for acoolant flow 1502 at varying points along the CAC 1512. The system 1500illustrates three settings for the control valve 1510, but any number ofsettings including full bypass of the coolant are possible. The system1500 is depicted providing coolant flow variation by varying the coolantinlet flow position. Alternatively or additionally, the system 1500 canvary the coolant outlet flow position, and/or may internally bypass aportion of the coolant flow within the CAC 1512 such that a portion ofthe nominal coolant flow area is not available, or is available at areduced effectiveness, for heat transfer.

The control valve 1510 schematically depicts a manipulation of theeffective flow area of the CAC 1512 on the coolant side, and may berealized through other mechanisms than with a valve. For example, andwithout limitation, one or more louvers, vents, or shrouding devices maybe utilized to expose varying amounts of the CAC 1512 to ram air. Wherehalf of the CAC 1512 is blocked from exposure to ram air, the effectiveflow area of the CAC 1512 on the coolant side is reduced and the totalheat transfer occurring in the CAC 1512 is reduced. The control valve1510 may be operable in a discrete position operation and/or in acontinuously variable control operation. Further, regions of theoperating range of the control valve 1510 may be discrete or continuous.

In certain embodiments, the control valve 1510 is controllable by an ECU116, and may be manipulated to control the temperature of the cooledintake air 1508 and/or a temperature of the intake manifold. Theoperations of the control valve 1510 may be coordinated with control ofan EGR temperature and/or flow rate. In certain embodiments, the ECU 116may control the temperature of the intake air 1508 to ensure that acondensation temperature (e.g. the saturation temperature) of the intakeair 1508 is not reached within the CAC 1512. The control of the intakeair 1506 above the condensation/saturation temperature may be performedwith the use of humidity sensors, humidity data provided to the systemthrough a datalink or network communication, and/or through conservativeestimates of the humidity (e.g. assuming 100% relative humidity, usingconservative humidity values based on available date and location data,etc.) to ensure that the condensation/saturation temperature of thecooled intake air 1508 is not reached.

Presently known CAC bypass devices can be utilized to manipulate theintake manifold temperature. However, presently known CAC bypass devicesbypass some or all of the intake air flow around the CAC. Accordingly,while the final temperature of the intake air in such a device may beachievable to a selected value, the temperature of some portion of theintake air may be brought below the condensation temperature resultingin undesirable liquid water occurring in the intake air system. Thesystem 1500 is an example system providing for control of the intake air1508 temperature to a selectable value without providing sub-cooling inportions of the intake air.

Referencing FIG. 16, an example controllable charge air cooler system1600 is depicted. The system 1600 differs from the system 1500 in thatthe intake air side of the CAC 1512 is controllable. Various controlvalves 1602, 1604, 1606, 1608 depict the intake air 1506 bypassing someor all of the CAC 1512. In contrast to presently known systems, theintake air bypasses the CAC 1512 in a manner that does not providesub-cooling of portions of the intake air 1506, thereby keeping theintake air 1506 above the condensation/saturation temperature. Thesystem 1500, 1600 are not exclusive, and the control valves 1510, 1602,1604, 1606, 1608 could be provided on the same system, although such anembodiment is not depicted.

The system 1600 is depicted providing intake air flow variation byvarying the intake air inlet flow position. Alternatively oradditionally, the system 1600 can vary the intake air outlet flowposition, and/or may internally bypass a portion of the intake air flowwithin the CAC 1512 such that a portion of the nominal intake air flowarea is not available, or is available at a reduced effectiveness, forheat transfer.

Referencing FIG. 17, another embodiment of a controllable charge aircooler system 1700 is depicted. The system 1700 differs from the system1500 in that a variable control valve 1702 changes a coolant side flowrate through the CAC 1512. For an engine or liquid coolant based system1700, the control valve 1702 may bypass a portion of the liquid coolantflow and/or reduce a flow rate of the liquid coolant flow. For anair-to-air CAC 1512, the control valve 1702 may be a vent, louvre,shroud, or other device that reduces a flow rate of ambient air acrossthe CAC 1512. In contrast to the system 1500, rather than blocking aportion of the CAC 1512 from ambient air impingement, the system 1700reduces the flow rate. However, a system (not depicted) may mix featuresof the system 1500 and the system 1700, for example reducing the coolantflow rate and/or reducing the coolant effective flow area.

As is evident from the figures and text presented above, a variety ofembodiments according to the present disclosure are contemplated.

An example set of embodiments is a system including an internalcombustion engine having an intake system that delivers induction gas toan intake manifold of the engine, and a fuel system that provides amixed fuel and air charge to a combustion chamber of the engine. Thesystem further includes a compressor coupled to an inlet of the intakesystem, and an exhaust gas recirculation (EGR) system that recirculatesexhaust gas to the intake system. The EGR system includes an EGRtemperature adjustment device. The system further includes an electroniccontrol unit (ECU) that interprets a parameter affecting an operation ofthe engine, that determines a knock index value in response to theparameter, and that provides an engine control command in response tothe knock index value exceeding a knock threshold value. The EGRtemperature adjustment device is responsive to the engine controlcommand.

In certain further embodiments, the EGR system is fluidly coupled to theintake system at a position upstream of the compressor. In still furtherembodiments, the EGR system is fluidly coupled to an engine exhaust flowat a position downstream of a turbine, where the example system includesa turbocharger including the compressor and the turbine. In certainembodiments, the EGR system is fluidly coupled to the engine exhaustflow at a position downstream of a particulate filter disposed in theengine exhaust flow, and the system further includes an exhaust throttleoperationally coupled to the exhaust flow at a position downstream ofthe EGR system.

In certain embodiments, the parameter affecting the operation of theengine comprises includes an engine speed value, an engine torque value,an intake manifold temperature, an EGR temperature, and/or an intakemanifold pressure. In certain embodiments, the EGR temperatureadjustment device includes an EGR cooler bypass valve, a low temperaturecoolant valve, a high temperature coolant valve, and/or an EGR routingvalve. Example EGR routing valves include, without limitation, a valveto bypass at least one EGR routing component (e.g. an EGR cooler), avalve to adjust an EGR outlet location, and/or a valve to adjust an EGRinlet location.

An example system includes a charge air cooler that cools inductiongases at a position between the compressor and the intake system, wherethe charge air cooler bypass valve selectively bypasses induction gasesaround the charge air cooler. Selectively bypassing includes partiallyor completely bypassing, at a continuously or discretely selectablequantity. The example system includes the charge air cooler bypass valvebeing responsive to the engine control command.

Another example system includes a high temperature coolant and a lowtemperature coolant, where the EGR temperature adjustment deviceselectively couples each of the high temperature coolant and the lowtemperature coolant to the recirculated exhaust gas. The EGR temperatureadjustment device selectively couples each of the high temperaturecoolant and low temperature coolant at continuously or discretelyselectable flow amounts, coupling one or both of the high temperaturecoolant and the low temperature coolant sequentially or simultaneously.An example system further includes the EGR temperature adjustment deviceprovide a selectable amount of each of the high temperature coolant andthe low temperature coolant to the recirculated exhaust gas to the EGRcooler.

In certain embodiments, the system includes a variable valve timing(VVT) system, where the VVT system is responsive to the engine controlcommand. The VVT system may be binary (i.e. two valve timing modes),continuously or discretely variable, and/or the valve timing for eachvalve may be completely independently controllable. In certainembodiments the fuel system further provides a fuel directly to thecombustion chamber. The fuel added directly to the combustion chambermay be the same fuel type as the fuel provided as part of the mixedfuel, and/or the fuel added directly to the combustion chamber may be adistinct fuel type from the fuel provided as part of the mixed fuel.

Another example set of embodiments is a method including interpreting aparameter affecting an operation of an internal combustion engine,determining a knock index value in response to the parameter, andreducing an intake manifold temperature in response to the knock indexvalue exceeding a knock threshold value. In certain embodiments, thereducing the intake manifold temperature includes reducing an exhaustgas recirculation (EGR) gas temperature. The operation to reduce the EGRgas temperature includes, in certain embodiments, operating a lowtemperature EGR cooler. The operation of the low temperature EGR coolerincludes operating the EGR cooler with a coolant having a reducedtemperature, with a coolant having an increased coolant flow rate,and/or an EGR cooler having an increased effective thermal contact areabetween the EGR gases and the coolant.

In certain embodiments, the method includes reducing an engine exhaustbackpressure in response to the knock index value exceeding the knockthreshold value. The operation to reduce an engine exhaust backpressure,in certain embodiments, thereby reduces residual gases in the combustionchamber. The operation to reduce the engine exhaust backpressureincludes, in certain embodiments, reducing an EGR flowing pressure,adjusting an EGR flow route, adjusting a variable geometry turbineposition, and/or adjusting an exhaust throttle position.

An example method includes adjusting a variable valve timing system inresponse to the knock index value exceeding the knock threshold value.In certain embodiments, the method includes fueling the engine at leastpartially by direct injection in response to the knock index valueexceeding the knock threshold value. Yet another example method includesreducing an intake manifold temperature by operating a charge air coolerbypass.

Yet another example set of embodiments is a system including an internalcombustion engine having an intake system that delivers induction gas toan intake manifold of the engine, and a fuel system that provides amixed fuel and air charge to a combustion chamber of the engine. Thesystem further includes a compressor coupled to an inlet of the intakesystem, and a low pressure exhaust gas recirculation (EGR) system thatrecirculates exhaust gas to the intake system. The example systemincludes a means for determining a knock index value and a means forreducing a likelihood of engine knock in response to the knock indexvalue exceeding a knock threshold value. The example system furtherincludes a means for reducing a likelihood of engine knock in responseto the knock index value exceeding a knock threshold value.

In certain embodiments, the system further includes a means forregenerating a particulate filter operationally coupled to an engineexhaust system including a three-way catalyst. An example systemincludes a means for flowing EGR when a temperature of the EGR is belowa condensation limit temperature for the EGR. The condensation limittemperature for the EGR includes, in certain embodiments, that EGR gaseshaving a present composition (including water fraction) and heattransfer environment will drop to a dew point temperature of the EGRgases within the EGR flow path, and/or within the EGR cooler.

Still another example set of embodiments is a method including operatinga spark ignition engine, flowing low pressure exhaust gas recirculation(EGR) from an exhaust to an inlet of the spark ignition engine,interpreting a parameter affecting an operation of the spark ignitionengine, determining a knock index value in response to the parameter,and reducing a likelihood of engine knock in response to the knock indexvalue exceeding a knock threshold value. In certain further embodiments,the method includes reducing the likelihood of engine knock by reducingan intake manifold temperature of the spark ignition engine. In certainstill further embodiments, the method includes reducing the intakemanifold temperature by bypassing at least a portion of compressoroutlet gases and/or by at least partially bypassing an EGR cooler. Anexample method further includes reducing the likelihood of engine knockby reducing a coolant temperature for an EGR cooler, by reducing a sparkignition engine backpressure, by adjusting a valve timing for the sparkignition engine, and/or by at least partially fueling the spark ignitionengine by direct injection.

Any theory, mechanism of operation, proof, or finding stated herein ismeant to further enhance understanding of embodiments of the presentinvention and is not intended to make the present invention in any waydependent upon such theory, mechanism of operation, proof, or finding.In reading the claims it is intended that when words such as “a,” “an,”“at least one,” “at least a portion” are used there is no intention tolimit the claim to only one item unless specifically stated to thecontrary in the claim. Further, when the language “at least a portion”and/or “a portion” is used the item may include a portion and/or theentire item unless specifically stated to the contrary. Whileembodiments of the invention have been illustrated and described indetail in the drawings and foregoing description, the same is to beconsidered as illustrative and not restrictive in character, it beingunderstood that only the selected embodiments have been shown anddescribed and that all changes, modifications and equivalents that comewithin the spirit of the invention as defined herein or by any of thefollowing claims are desired to be protected.

1-14. (canceled)
 15. A method, comprising: interpreting a parameteraffecting an operation of an internal combustion engine receiving acompressed intake air flow; determining a knock index value in responseto the parameter; and reducing an intake manifold temperature inresponse to the knock index value exceeding a knock threshold value. 16.The method of claim 15, wherein the reducing the intake manifoldtemperature comprises reducing an exhaust gas recirculation (EGR) gastemperature.
 17. The method of claim 16, wherein the reducing the EGRgas temperature comprises operating a low temperature EGR cooler. 18.The method of claim 15, further comprising reducing an engine exhaustbackpressure in response to the knock index value exceeding the knockthreshold value.
 19. The method of claim 18, wherein the reducing theengine exhaust backpressure comprises at least one operation selectedfrom the operations consisting of reducing an EGR flowing pressure,adjusting an EGR flow route, adjusting a variable geometry turbineposition, and adjusting an exhaust throttle position.
 20. The method ofclaim 15, further comprising adjusting a variable valve timing system inresponse to the knock index value exceeding the knock threshold value.21. The method of claim 15, further comprising fueling the engine atleast partially by direct injection in response to the knock index valueexceeding the knock threshold value.
 22. The method of claim 15, whereinthe reducing an intake manifold temperature comprises operating a chargeair cooler bypass. 23-43. (canceled)
 44. The method of claim 15, whereinreducing the intake manifold temperature comprises reducing atemperature of an exhaust gas recirculating to an intake system of theinternal combustion engine.
 45. The method of claim 44, wherein reducingthe temperature comprises selectively coupling one of a high temperaturecoolant and a low temperature coolant to an exhaust gas recirculationcooler that cools the exhaust gas recirculating to the intake system.46. The method of claim 15, further comprising recirculating an exhaustgas from a low pressure exhaust gas recirculation system of the internalcombustion engine.
 47. The method of claim 46, wherein low pressureexhaust recirculation system is connected at an intermediate position ofa three-way catalyst in an exhaust system of the internal combustionengine.
 48. A method, comprising: interpreting a parameter affecting anoperation of an internal combustion engine that receives a compressedintake air flow and a recirculated exhaust gas flow; determining a knockindex value in response to the parameter; and reducing an intakemanifold temperature in response to the knock index value exceeding aknock threshold value, wherein reducing the intake manifold temperatureincludes adjusting a temperature of the recirculated exhaust gas flow byproviding a selected amount of high temperature coolant and a selectedamount of low temperature coolant to a cooler that cools therecirculated exhaust gas flow.
 49. The method of claim 48, wherein therecirculated exhaust gas flow is fluidly coupled to an intake system ofthe internal combustion engine at a position upstream of the compressedintake air flow.
 50. The method of claim 49, wherein the recirculatedexhaust gas flow is fluidly coupled to an engine exhaust flow at aposition downstream of a turbine disposed in the engine exhaust flow.51. The method of claim 49, wherein the recirculated exhaust gas flow isfluidly coupled to the engine exhaust flow at a position downstream of aparticulate filter disposed in the engine exhaust flow.
 52. The methodof claim 49, wherein the recirculated exhaust gas flow is fluidlycoupled to the engine exhaust flow at a position intermediate of anaftertreatment component disposed in the engine exhaust flow.
 53. Themethod of claim 52, wherein the aftertreatment component is a three-waycatalyst.